Electrical switch



4 Sheets-Sheet l III 200 ELECTRICAL .SWITCH W. A. MASCIOLI ET AL FiledOCT.. ll, 195

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ELECTRICAL SWITCH Filed oct. 11, 195e 4 sheets-sheet 2 Inventaris?B/aZZer/I. Mascz'oZz', Henry am'd las teil?,

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ELECTRICAL SWITCH 4 Sheets-Sheet 3 Filed OCT.. ll, 1956 .f.Z./.n; n, .9www y was@ A @sfr paia MM. Awww.

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Nov. 12, 1957 ELECTRICAL SWITCH 4 Sheets-Sheet 4 Filed Oct. ll, 1956muy@ v E C Q n f @Q w `m ||L|I A U d um'lvl r a e W Q6! NQ Z 7. KQ..- n.NQ Wa @m SMP law; m W my QQ H y a United States Patent @thee PatentedNov. 12, 39527 ELECTRICAL SWITCH Walter A. Mascioli, Canton, Henry DavidEpstein, Boston, and Wilfred W. Cardin, Attleboro, Mass., assignors toMetals & Controls Corporation, Attleboro, ivi-ass., a corporation ofMassachusetts Application October 11, 1956, Serial No. 615,345

6 Claims. (Cl. 2lll) S8) This invention relates to a circuit breaker,and more particularly to a circuit breaker including a plurality ofsections each of which includes electrical contacts adapted to bemanually and/or automatically opened and closed.

An object of this invention is to provide such a circuit breaker havingimproved operating characteristics.

A further object of this invention is to provide such a circuit breakerwhich is capable of being built-up by means of a preassembled mainsubassembly which is then insertable into a casing.

A further object of this invention is to provide such a circuit breakerhaving high shock and vibration resistance. A further object of thisinvention is to provide such a circuitL breaker having such high shockand vibration characteristics along with individual loading andsimultaneous breaking of the contacts of the respective sections.

A further object of this invention is to provide such a circuit breakerwhich is compact, dependable in operation and economical to manufacture.

Other objects will be in part obvious and in part pointed outhereinafter.

The invention accordingly comprises the elements and combinations ofelements, features of construction, and arrangements of parts which willbe exemplified in the structures hereinafter described, and the scope ofthe application of which will be indicated in the following claims.

In the accompanying drawings, in which several of the various possibleembodiments of the invention are illustrated:

Fig, l is a plan view of an electrical device falling within the scopeof this invention;

Fig. 2 is a sectional view of the device in released, contacts-openposition, this view being taken along line 2 2 in each of Figs. 1 and 3and being on an enlarged scale over that of Fig. l, certain of the partsbeing broken r away for purposes of clarity of illustration;

Fig. 3 is a sectional view taken along line 3 3 in Fig. 2;

Fig. 4 is a bottom View of the device of this invention on the samescale as that of Fig. l;

Fig. 5 is a sectional view taken along line 5 5 in Fig. 3;

Fig. 6 is a sectional View taken along line 6 6 in Fig. 3, a portion ofthe internal `wall of the casing being broken away clearly to show therelationship between one of the retaining pins and its recess;

Fig. 7 is a sectional view taken along line Fig. 2;

Fig. 8 is a sectional View taken along line Fig. 2;

Fig. 9 is a view similar to Fig. 2 but showing the parts in actuated,contacts-closed position;

Fig. 10 is an isometric view of the latch-engageable member of theembodiment of this invention illustrated in the drawings; and

Fig. l1 is an isometric View of the latch thereof..

t will be recognized that certain parts in several of the figures in thedrawing have been omitted for the purpose of clarity of illustration.

The embodiment of this invention as particularly described herein takesthe form of the circuit breaker indiated generally by the numeral 2i?.Circuit breaker 20 includes a casing 22 formed of an insulating materialsuch as one of the customary molded plastics and having its upper endopen (as viewed in Fig. 2). Casing 22 provides a plurality of sectionsgenerally indicated by reference numerals 24, 26 and 2S, respectively,adjacent sections being divided by separators 3l) and 32, respectively.lt will be clear that the number of sections to be provided by thedevice may vary as determined by individual requirements. Separators 30and 32 have their opposite ends disposed in inwardly facing, opposedrecesses 34 and 36, and 38 and 46, respectively. Recesses 34, 36, 38 and40 are provided by casing 22 and extend to the open end of the casing.

Each of sections 24, 26 and 23, includes a lixed contact 42, a movablecontact 44 and means carrying the movable Contact for pivotal movementabout a common axis. This axis is coincident with the axis of each ofpivot pins 46, 48 and 5t), each of which is coaxial with the others.Pivot pin 48 is supported at its ends in opposed sockets provided by theadjacent portions of separators 3i) and 32. Each of pivot pins 46 and 50has one end disposed in like manner in a socket provided by the adjacentportion of the respectively adjacent separator. The opposite end ofpivot pin 46 is disposed at the bottom of a dove-tailed recess 52 whichextends to the open end of the casing. In like manner the opposite endof pivot pin Si) is disposed at the bottom of a similar recess 54.Retaining pins 56 and 58 are disposed in recesses 52 and 54,respectively, in abutment with the respectively adjacent pin thereby toretain that pin at the bottom of its respective recess in a manner to beparticularly described later in this description,

The means mounting the movable contact 44 of each of the sections forpivotal movement about the abovestated common axis includes acontact-carrying arm 60 pivotally mounted on its respective pivot pin.Also mounted on each of pivot pins 46, 48 and 5t) is a member 62. Member62 of each of the sections includes a loop 64 deformed therefrom toprovide spaced portions within which a common connecting link 66 isdisposed with a snug lit whereby all of members 62 are mounted formovement in unison about the said common axis. Connecting link 66 ispreferably formed of electrically insulating material and extends acrossall of the sections of the circuit breaker. it will be noted that eachof separators 3l) and 32 provides a slot 68, 70, respectively, for thereception of connecting link 66 throughout movement of members 62between opposite extreme pivotal positions.

Each of members 62 is resiliently biased away from the member 60 withwhich it cooperates by means of a 'spring 72. Opposed shoulders providedby members 60 and 62 meet at 71 to limit the extent to which thesemembers are biased away from each other. It will be apparent that solong as no restraining force is applied to any one of members 6l), eachof these members will pivot in unison about said common axis along withits respective cooperating member 62.

Member 62 of each of the outer sections has one end of a tension spring'73 connected thereto, the other end of which is connected to a pin 75.The internal walls of casing 22 provide opposed recesses 67, 67, each ofwhich lies opposite a similar recess 69, 69 provided by the adjacentseparator. Each of recesses 67, 67, 69, 69 extends to the open end ofcasing 22. Each of pins 75, has

its opposite ends disposed at the bottom of one of these pairs ofrecesses. Since members 62 of the three sections are secured to commonconnecting link 66, tension springs 73, 73 resiliently bias all three ofmembers 62, along with their respectively cooperating members 60, awayfrom the fixed contact 42 of their respective sections.

In one of the sections, preferably the centermost section (or one of thecentermost sections if more than three sections are provided), a latchengageable member 74 is provided and mounted for pivotal movement aboutthe aforementioned pivot pin of that section. Latch-engageable member 74is movable about said common axis by means later to be described tobring a projection or abutment 76 carried thereby into engagement withan opposed projection or abutment 78 ixedly carried by alatch 80.Referring to Fig. l0, latch-engageable member 74 provides an eye 82 forattachment of one end of a tension spring 84, the other end of whichspring is supported by a pin 86. Separators 30 and 43:2 provide opposed,inwardly extending recesses 88 and 90, respectively, for the receptionof the opposite ends of pin 86 whereby the pin is mounted in recesses 88and 90 in the same manner that pins 75, 75 are mounted in theirrespective recesses. By means of tension spring V84 and itsabove-described connections, latch-engageable member 74 is resilientlybiased in a clockwise direction about said common axis as viewed in Fig.2.

Latch 80 includes a latch bar 94 formed of a suitable electricallyinsulating material. Mounted in xed, mutually isolated relationship toeach other on latch bar 94 are a plurality of members 96, 98 and 100.Each of members 96 and 100 includes an integral leg 192 and 104,respectively, having its distal end secured as by brazing or welding toa pin 106 and 108, respectively. The inner ends of pins 106 and 1118 aredisposed in sockets 110 and 112, respectively, provided by respectiveseparators 30 and 32. The outer ends of pins 186 and '108 are disposedat the bottom of recesses 114 and 116, respectively, provided by therespectively adjacent portions of the casing. Each of recesses 114 and116 extends to the open end of casing 22. l

One of members 96, 98 and 108 is disposed in each of sections 24, 26 and28 and each of these members acts as the armature of an electromagnet inVa manner now to be described. The electromagnet means foreach ofmembers 96 and 100 is or may be substantially identical to the other andtherefore a detailed description of one will suffice for both. Referringto Fig. 5, the yelectromagnet means for armature 100 isgenerallyindicated by the reference numeral 118 and includes a block 120having two pole pieces 122 and 124 integrally secured thereto.vElectrically conductive means 126 extends from one end portion 128,which acts as a terminal, into the interior of the casing 22 and coursesin a counterclockwise path about pole piece 124, between the polepieces, and then in a clockwise path about pole piece 122, alllas.viewed in Fig. 7. Electrically conductive means 126 extends upwardlyabove pole pieces 122 and 124 as viewed in Fig. to a point 129 at whichit is secured in electrically conductive relationship toa thermostaticmember 130 for a purpose later to become apparent. Block 12() is securedin fixed relation to casing 22 by means of a headed screw 132 which isthreaded Ain tightened engagement with an aperture in the block. Each ofpole pieces 122 and -124 is provided with a sleeve 134, 136,respectively, which is formed of electrically insulating material. Inthis manner, each of pole pieces 122 and 124 is electrically insulatedfrom conductor 126. It will'be apparent that upon the flow of current ofsuiiicient magnitude through electrically conductive means 126,electromagnet means A118 will be energized to attract armature V101) 'toAthe left as viewed in Fig. 5 thereby swinging latch bar Theelectromagnet means for armature 9,8.isormay be substantially identicalwith that for each of armatures 96 and 100 except as pointed out asfollows. Referring to Fig. 2, pole piece 138 is formed with a diameterslightly reduced over that of each of the other pole pieces toaccommodate a compression spring 140 which lies in concentric relationwith that pole piece and the insulating sleeve thereabout. Spring 140has its opposite ends disposed against block 142 of this electromagnetmeans and armature 98, respectively. It will be apparentrthatcompression spring 140 resiliently biases latch 80 in thecounterclockwise direction as viewed in Fig. 2, the extent ofcounterclockwise movement of the latch being determined by engagement oflatch bar 94 with the adjacent edge of openings 144 and 146 inseparators 30 and 32, respectively.

Additional means areV provided for swinging latch bar 94 in a clockwisedirection as viewed in Fig. 2, these means being operable bothindependently and in combination with the electromagnetic means. Theseadditional means take the form of a plurality of thermally responsivemembers 130, one for each of the sections. All of these additional meansbeing of substantially identical form, only the additional means 130which is disposed in section 28 need be particularly described.Thermally responsive means 130 takes the form of a bimetallic elementwhich, as stated above, is secured in electrically conductiverelationship with conductor 126. The distal end of bimetallic member 130is connected as by brazing or welding at 148 to one end of a exible lead150, the other end of which is secured in electrically conductiverelationship to contact-carrying arm 60 at 152. It will now be apparentthat an electrically conductive path is established leading from movablecontact 44 of each of the Sections through the following respectiveparts of each section: contact-carrying arm 60, flexible lead 150,bimetallic element '138, conductor 126 and terminal 128. Upon arise intemperature of bimetallic member 130, due to current flowing throughbimetallic element 130, the distal end of this member is movable to theleft as viewed in Fig. 5. The extent of movement of the distal end ofbimetallic member 130 to the left as viewed in Pig. 5 is proportional tothe magnitude of the current therethrough. Upon the flow of current ofsuflicient magnitude through `bimetallic member 130, the distal end ofthis member is movable against that one of projections '153, 154 andk155 carried by the respective one of members '96, 98 and 108 o'f thatsection thereby to swing latch bar 94 to the left in a clockwisedirection about the axis of pins '106 and 108 as viewed in Fig. 5. Asnoted in Figs. 7 and 8, member 130 in sec- `tion 28 may be canted in theopposite direction from that of the others in order to dispose itsdistal end nearer latch abutment 78 than otherwise would be the case.

Electrically conductive means 126 of each of the sections includes anextension -156 which mounts the junction between itself and thebimetallic member 138 to which it is secured, in spaced relation to theadjacent wall of the casing (see Figs. 5 and 7).

It will be apparent ffrom the above that latch bar 94 Ais swingable tothe left in a clockwise direction aboutrthe axis ofpins 106 and 108 (asviewed in each of Figs. 2, 5, 6 and 9) under the influence of each ofthe electromagnetic means of each of the sections and under theinfluence of each of the thermally responsive means of each of thesections, each independently or in combination with Vany one or more ofthe others. Until latch bar 9 4 is so moved to the left as viewed inFigs. 2, 5, 6 and 9, vthe latch 80 is operable releasably to retain themovable contact 44 of each of the sections in electrically conductiveengagement with its respective fixed contact 42 in a manner pointed outas follows. Y

With reference to Figs. 2 and 8, -latch-engageablc member 74 of the`center section 26 providesra cam surface 160 for cooperation with aroller 1162. `Member 62 of center lsectionlti provides :acam .surface.1164 for.co-

operation with r011ers`166, 166. Rollers 162, 166 and 166 (see Fig. 8)are respectively mounted in coaxial relationship for rotation about apin 168 which has its ends iixed in mutually spaced members 170, 170.Members 170, 170 and pin 168 together form a yoke pivotally mounted formovement about a pin 172. A link 171 has its opposite ends secured tomembers 170, 170, respectively, to aid in rigidifying this yoke. Pin 172passes in loosely intertting engagement with apertures in the distal endof each of members 170, 170 and in similar interfitting engagement withan extension 174 of a push button 176. As noted in Fig. 2, a sleeve 178disposed about extension 174 is confined within a hub 180 forsubstantially rectilinear movement with push button 176 and extension174 toward and away from the interior of casing 22. Hub 180 is suitablysecured in xed relation to cover member 182 about an aperture in thelatter through which extension 174 extends. The opposite ends of pin 172ride in opposed recesses 183, 183, each of which extends to the open endof the casing 22. Recesses 183, 183 are provided by separators 30 and 32as best shown in Fig. 3, these recesses guiding pin 172 for rectilinearmovement in the same opposite directions as that of extension 174. Aninsulating piece 184 is disposed between cover member 182 and the openend of casing 22. insulating piece 184 is secured tightly between coverrnember 182 and the open end of casing 22 by means such as headed screws186 (see Fig. l) which may be threaded in tightened engagement withadjacent apertures provided by casing member 22.

The operation of circuit breaker may be described as follows. With theparts in the position shown in Figs. 2, 3 and 5-8, in which the movablecontact 44 of each of sections 24, 26 and 28 is in separated relationwith respect to its fixed Contact 42, each of arms 62 is resilientlybiased away from contact-carrying member 60 of its section to the extentlimited by the engagement of the respective shoulders of these membersat 71. Also, member 62 and contact-carrying member 60 of each of thesections is resiliently biased upwardly as viewed in Fig. 2 under theinuence of springs 73, 73, and latchengageable member 74 is resilientlybiased upwardly as viewed in Fig. 2 under the iniluence of spring 84. Itwill be noted that with the parts in the position of Figs. 2, 3 and 5-8,the combined force exerted by springs 72, 72, 72 is greater than thecombined force exerted by springs 73, 73, and that the combined forceexerted by springs 73, 73 is greater than the force exerted by spring84. The result is that upon depression of push button 176, rollers 166ride along cam 164 provided by member 62 whereby roller 162 movesagainst cam surface 160 provided by latch-engageable member 74 therebyto swing the latch-engageable member in a counterclockwise directionabout the axis of pin 48 until projection 76 moves into engagement withabutment 78 provided by latch 80. Thereafter, roller 162 moves along camsurface 160 provided by latch-engageable member 74 thereby to moverollers 166, 166 against cam surface 164 provided by member 62, causingmember 62 along with member 60 to pivot in a clockwise direction aboutthe axis of pin 48. Members 62 and 60 pivot in unison with each otheruntil movable Contact 44 cornes into engagement with fixed contact 42.At this point lost motion of member 60 with respect to member 62 ensueswhereby member 60 remains stationary while member 62 continues to moveto the position shown in Fig. 9 at which the respective shouldersprovided by members 60 and '62 are separated from each other. it will benoted that with the parts in the position shown in Fig. 9, Wedging meansor rollers 166, 166 and 162 have moved into an over-center position withrespect to the latch-engageable member 74 and member 62. With the partsin the position of Fig. 9, it will also be noted that an electricallyconductive path is established from terminal 128 to iixed contact 42.'Each of fixed contacts 42 is fxedly secured in electrically conductiverelationship with a terminal 190. Since member 62 of each of thesections is secured to connecting link 66 as previously described, allof the members 62 along with their respective contact-carrying arms 60are disposed in like manner with the movable contact 44 of each of theserespective sections in electrically conductive engagement with itsrespective fixed contact 42.

It will be recognized that by wedging the parts into over-centerrelationship with the structure as described above, the circuit breakerinherently possesses high shock and vibration resistance, and this alongwith the feature that each set of cooperating contacts is individuallyloaded into its contacts-closed position. Furthermore, since the meansfor moving each of the movable contacts into contacts-closed position isor may be identical with each of the others and since these respectivemeans are constrained for movement by connection to a common connectinglink, this feature of individual loading of the respective sets ofcontacts is coupled with the feature whereby a comparatively high degreeof simultaneity of breaking of the respective sets of contacts iscapable of being eiected. To illustrate the high degree of simultaneityof breaking of the respective sets of contacts, it is noted that, undertest, the exemplary circuit breaker ernbodiment shown and describedherein was found to have accomplished breaking of the contacts of allthree of the sections within a fraction of a single cycle when thiscircuit breaker was operatively connected in a system utilizingalternating current of 400 cycles per second.

The electrically conductive path between terminals 128 and 190 of eachof the sections will remain intact until the latched condition describedabove is disrupted in any one of several different ways. First, pushbutton 176 may be manually and forcibly retracted from the wedging,over-center relationship shown in Fig. 9 whereby the parts will quicklyreturn under the influence of the respective springs to the positionshown in Fig. 2. Alternatively, the parts are quickly movable from theposition shown in Figs. 2, 3 and 5-8 to the position shown in Fig. 9upon movement of abutment 78 carried by latch out from under projection76 carried by latch-engageable member 74. As noted above, latch 80 ismovable to the left in a clockwise direction about the axis of pins 106and 108 as viewed in Fig. 2 under the independent or combined action ofany one of the electromagnetic means or thermally responsive means ofeach of sections 24, 26 and 28. That is, for example, under a moderatecurrent overload through any one of bimetal members 130, the distal endof that bimetal member is movable against its respective projection 154to disengage abutment 78 carried by the latch from projection 76 carriedby the latch-engageable member 74. Also, upon a current overload ofcamparatively high magnitude such as that as might be occasioned by ashort-circuit, the electromagnet means of any one of the sections 24, 26and 28 will be energized suciently to attract the armature of thatrespective section thereby to release abutment 78 from projection 76.

Upon movement of latch 80 in a clockwise direction about the axis ofpins 106 and 108, latch-engageable member 74 will first pivot in acounterclockwise direction since the combined force exerted by springs73, 73 added to the combined force exerted by all of springs 72, '72, 72is of a much greater magnitude than that of the force exerted by spring84. In this manner the parts are unlatched and member 62 in each of thesections moves upwardly as viewed in Fig. 2 thereby moving roller 162against latch-engageable member 74 and causing the latter to pivot in acounterclockwise direction against the bias of spring 84. The combinedeiect of springs 73, 73 and the springs 72 of all of the respectivesections, is to snap the shoulder provided by each of members 62 againstthe adjacent Shoulder provided by the respective one of members60'thereby to snap the movable contact 44 of each of the sectionsrapidly away from the xed contact 42 with which it is associated. Inthis manner, welding or any other sticking between each of the movablecontacts and the fixed contact with which it cooperates will beeiectively broken. Continued movement of members 62 and 60 brings theseparts back to the position of Fig. 2. Meanwhile, the initialcounterclockwise movement of latch-engageable member 74 about the axisof pin 48 in combination with the effect of spring 84 and roller 162results in movement of this member whereby slots 192, 192 provided bymember 74 ride along pin 48. Latch-engageable member 74 and push button176 then return to Vthe position shown in Fig. 2 under the influence ofspring 84. For additional details of the cooperative relationship amongthe latching and actuating parts in center section 26, reference may behad to United States Patent 2,613,296 granted on October7, 1952, to M.B. Wood.

By virtueiof openings 144 and 146 in separators 30 and 32, respectively,each of thermally responsive members 130 is disposed in mutually heatingrelationship to each of the others., Accordingly, if a current overloadwere to develop through two or more of the bimetallic members 130, Veachof whichvwas thereby individually incapable of moving the distal end of`that member 130 suiciently to disengage latch 80 from projection 76, thecombined etfect of these bimetallic members could so release latch 80.

In assembling circuit breaker 20, the xed contact 42 of eachof thesections along with the terminal 190 secured thereto may be xed to thecasing by means such as a pair of Vrivets 193. With the exception of theactuating means and insulating Vpiece 184, all of the internal partstofthe device may be preassembled into a main subas'sembly which may beinserted as a unit into the casing. -A headed screw 194V may betightened in threaded engagement with a lateral extension 196 providedby each of terminals V128 thereby vaiding in xedly securing theelectrically conductive means 126 and bimetal member 130 carried therebyto the casing. Headed screws 132 may be screwed into tightened threadedengagement with the respective aperture -in the block of theelectromagnet means of each ofthe sections thereby xedly to secure theseelectromagnet means to the casing. Adjusting screws 198 may be insertedthrough the casing into each of the respective sections threadedlyto'engage an aperture in the intermediate portion ofthe electricallyconductive Ameans 126 of each of the sections for adjustment of therespective thermally responsive members 13,0-

Subsequently, each of pins 86, 75, 75 may be engaged `with itsrespectivespring and disposed in its respective recesses. A retainingpiece 200 formed of electrically insulating material may be placedagainst-each of pins 75, 75 andr86, each of these pieces having itsopposite ends disposed in the same recesses as the pin against which itis placed. Retaining pins 56 and 58 may then be inserted in dovetaile'drecesses 52 and 54, respectively, against the respective end of pins 46and Sil. Insulating piece` 184 may be placed against the inner face ofcover member 182, after which sleeve 178 and push button 176 areinserted through'hub 180 and assembled with the yoke formed by rollers162, 166, 166, pin 168 and arms V170, 170. YPin 172 may then be insertedin the aligned apertures provided by arm 170, push button eX- tension,174 and the other arm 170, the opposite ends of pin 172 are insertedinto recesses 183, 183 and the cover member is then secured in place bymeans of headed screws 186. With cover member 182 so disposed,insulating piece 184 bears snugly against each of retaining parts 56,58, A21N), 201) and 200, thereby effectively retaining the respectiveparts against which these retaining parts bear. ,Y One of the featuresYof this invention leading to economy of manufacture is the fact thatboth of separators 30, 32 are or may be identical as are or may be allof the conductors 126, all of the members 62, all of contact-carryingarms 60, all of terminals 190 with their integral fixed contacts 42, allof springs 72, two of the electromagnet means-118, 118 and two of thebimetallic members 13,0.Y

It will be noted that since the latching mechanism of this invention isseparate from each of bimetallic members 130, the latter members are notconstantly loaded under the latchingforces. One advantage of Vthisfe'ature is that deformation of member due to such loading under hightemperature conditions is avoided. Another advantage of a deviceincorporating this invention is that a novel arrangement is providedwhereby a common latch, under the Iiniluence of means responsive to afault in the circuit of any one of the sections, is effectivesimultaneously to open the contacts of all of the sections. Also, itwill be apparent that circuit breaker 20 is trip-free of push button176. That is, upon the occurrence of a fault in the circuit of any oneof the sections, the contacts of all of the sections will be opened eventhough push button 176 is held in depressed position; and, so long assuch a fault exists, depression of the push button will be ineffectiveto close the contacts of any of the sections.

In view of the above, it will be seen that the several objects of theinvention are achieved and other advantageous results are attained.

As many changes could be made in the above constructions withoutdeparting from the scope of the invention, it is intended that allmatter contained in the above description or shown in the accompanyingdrawings, shall be interpreted as illustrative and not in a limitingsense.

We claim:

l. In combination: a plurality of iixed contacts; a plurality of armspivotally mounted for movement about a common axis, each of said armscarrying a movable contact for cooperation with one of said fixedcontacts; a latch-engageable member mounted for pivotal movement aboutsaid common axis; a plurality of additional members, eachof saidadditional members being cooperable with one of said arms and mountedfor pivotal movement about said common axis; means resiliently biasingeach of said additional members away from the arm with which it iscooperable; means resiliently biasing said latch-engageable member andone of said additional members toward eachother; wedging means operableto wedge said latch-engageable member and said one additional memberapart into over-center relationship; a latch for releasably retainingsaid one additional member and said latch-engageable member in saidover-center relationship when engaged with said latch-engageable member;and all of said additional members being secured to a common connectinglink for movement in unison with each other; whereby movement of saidwedging means to the over-center position is effective simultaneously tomove each of said additional members and the arm with which it iscooperable to bring each of said movable contacts into engagement withits re- Vspective xed contact and then to effect lost-motion betweeneach of said arms and the additional member `cooperable therewithagainst the resilient bias of the taneous separation of each of saidmovable contacts from its respective fixed contact; and saidthermostatic members being in mutually heating relationship to eachother.

3. The device as set forth in claim Vl including a plurality ofelectrically conductive members, one electrically connected to each ofsaid movable contacts, a plurality of electromagnet means mounted onsaid casing and each being disposed for energization adjacent one ofsaid electrically conductive members, a plurality of armatures fixedlycarried by said latch, each of said armatures being movable with saidlatch toward one of said electromagnet means in response to a currentoverload through the respective electrically conductive member therebyto release said latch-engageable member from engagement with said latch.

4. In combination: an open-ended casing formed of electricallyinsulating material and providing a plurality of sections; a separatorformed of electrically insulating material disposed between adjacentsections; a pair of inwardly extending, opposed recesses provided bysaid casing for each separator, each of said recesses extending to theopen end of said casing; each separator having its opposite endsdisposed in its pair of recesses; each of said sections including afixed contact carried by said casing, a movable contact cooperable witheach of said fixed contacts and means carrying each of said movablecontacts for pivotal movement about a common axis; said last-mentionedmeans of each of the sections being identical with each of the others; acommon connecting link extending across said separators and fixed to allof said movable contact-carrying means thereby to constrain all of saidmovable contact-carrying means for movement in unison with each otherabout lsaid common axis; a movable latch extending across saidseparators; each separator providing a slot for the reception of saidconnecting link and a slot for the reception of said latch; alatch-engageable member mounted for movement about said common axis;means movable against said latchengageable member and one of saidmovable contactcarrying means to pivot said latch-engageable member andsaid one contact-carrying means about said axis and apart intoover-center relationship whereby said latchengageable member moves intoreleasably locked engagement with said latch and vsaid contact-carryingmeans move their respective movable contacts into engagement with theirrespective iixed contacts.

5. The device as set forth in claim 4 including a plurality ofthermostatic members, one electrically connected to each of said movablecontacts, each of said thermostatic members being independently movableagainst said latch upon a current overload therethrough to release saidlatch-engageable member thereby to effect simultaneous separation ofeach of said movable contacts from its respective fixed contact; andsaid thermostatic members being in mutually heating relationship to eachother.

6. In combination: a casing; a pair of cam members pivotally mounted formovement about a common axis; wedging means cooperable with said cammembers to wedge the cam members apart into over-center relationship; alatch engageable with one of said cam members to retain that cam memberin said over-center relationship; a plurality of fixed contacts mountedon said casing; a plurality of spaced arm members pivotally mounted formovement about said axis and each carrying a movable contact forcooperation with one of said fixed contacts; said other cam member beingcooperable with one of said arm members; an additional member cooperablewith each of the other of said arm members, pivotally mounted formovement about said axis and fixed, along with said other cam member, toa common connecting link for movement in unison with each other; meansresiliently biasing each of said arm members away from the member withwhich it is cooperable; means resiliently biasing all of the membersfixed to said common connecting link away from their respective fixedcontacts; whereby movement of said wedging means to the overcenterposition is effective simultaneously to move each set of the cooperatingmembers to bring each of said movable contacts into engagement with itsrespective fixed contact after which lost-motion ensues between each ofsaid arm members and the member with which it is cooperable,

References Cited in the file of this patent UNITED STATES PATENTS2,190,517 Jennings Feb. 13, 1940 2,214,695 Jennings Sept. l0, 19402,449,486 Killian et al. Sept. 14, 1948 2,613,296 Wood Oct. 7, 19522,673,264 Cole Mar. 23, 1954 2,678,359 Brumfeld May ll, 1954

